Percussion fuse



July 7, 1959 R. LEROY PERCUSSION FUSE Filed April 23, 1957 2,893,322 PERCUSSION FUSE Ren Leroy, Le Locle, Switzerland, assignor to Dixi S.A., Le Locle, Switzerlan'd Application April 23, 1957, Serial No. 654,596

Claims priority, application Germany September 5, 1956 3 Claims. (Cl. 102-76) My invention has for its object a percussion fuse for missiles, chiefly for mine throwers, said fuse incorporating a firing device adapted topivot in an inner chamber formed inside the fuse body and incorporating the detonator and the striker, associated with safety means operating on a mechanical delay principle.

Said percussion fuse is characterised according to my invention through the fact that the safety procedure is controlled through two cooperating interengaging coaxial pistons subjected to an elastic force, one of said pistons providing for the delay in the operation of the safety releasing means at the moment of the firing while the other piston acts subsequently so as to produce directly the release of the safety means,

Accompanying drawings illustrate by Way of example and by no means in a binding sense a preferred embodiment of the said invention. In said drawings:

Fig. l is a vertical cross-sectionpas sing through the axis of the fuse. i

Fig. 2 is a transverse cross-section through line II-II of Fig. 1.

Fig. 3 is a similar section, showing however the different parts of the fuse in a different relative position.

Fig. 4 is a vertical cross-section of a portion of the fuse through line lV IV of Fig. 3. a

The body of the fuse includes three hollow cylinders or casings threadedly fitted inside one another coaxially as illustrated at 1, 2 and 3. The hollow cylinder 1- is provided with an axial bore which serves for guiding an outer piston constituted by a sliding sleeve 4 and by a disc 4a secured to the outer end of the sleeve 4. On said disc 4:: forming the bottom of the piston is secured a piston rod 5 extending into the body of the hollow chamber formed inside the next hollow cylinder 2.

The outer piston 4-4a is held normally in the position illustrated in Fig. 1 by means of a locking ball 6 and in this position its inner end engages the outer end of the wall of the hollow cylinder 2, which end forms an abutment for said piston. The locking ball 6 is partly engaged inside an annular groove 1a formed in the inner wall of the hollow cylinder 1 and it also engages partly the opening 4b formed in the sleeve 4 constituting the side wall of the piston 4-461. The inner cylindrical surface of the sleeve 4 of the latter serves for guiding the inner piston 7. V

The rod 5 of the outer piston 44a passes with a clearance through the bottom of said second inner piston 7 which is urged by a compression-spring 8 into contact with a projection or hub formed on the inner surface of the bottom 4a of the outer piston, said hub serving for the securing of the piston rod 5.

Said compression spring 8 engages through one end the transverse partition 2a closing the medial hollow cylinder 2 while the other end of said spring engages the sealing disc 9 provided with a central guiding member or hub through which said disc engages slidingly the piston rod 5 so as to move axially of the latter. The spring 8 urges said disc 9 into contact with the inner surface 2,893,322 Patented July 7, 1959 of the bottom of the piston 7, so that said disc 9 closes fluidtightly the inner end of the annular clearance between the piston rod 5 and the bottom of the piston 7 through which said piston rod slides. The sidewall of the piston 7 extends, for the position of the different parts illustrated in Fig. l, sufficiently far towards the hollow cylinder 2. so that the locking ball 6 may be held fast in its locking position. At the outer end of the axial bore in the hollow cylinder 1 is secured transversely a diaphragm 10 so as to form outside the bottom 4a of the piston 4 a piston chamber 11 which is fluidtightly closed on its outer side by said diaphragm.

Between the transverse partition 2a inside the central cylinder 2 and the cover of the hollow cylinder 3 facing it, and which is provided with an axial priming hole 3a, there is formed a cylindrical chamber 12 in which is revolubly fitted a carrier member 13 in which are eccentrically secured the detonator and the striker. The rotary axis of said carrier member 13 extends to the outside of the fuse axis in parallelism with the latter. Said axis is constituted in practice by a spindle 14 (Figs. 2, 3 and 4), one of the ends of which rests in the cover of the hollow cylinder 3 and the other end is carried by the partition 2a. The carrier member 13 for the detonator is provided with a longitudinal bore 13b extending in parallelism with this rotary axis of carrier member 13'and the axis of which passes through a point of a circle drawn round said rotary axis of the carrier member 13 with a radius equal to the distance between the last mentioned axis and the axis of the fuse so that said bore 131: may register with the latter axis and cooperate then with the safety means as disclosed hereinafter. On the same circle as this longitudinal bore is also provided the axis of the actual detonator 15 so that the latter may be readily substituted for the bore 13b upon firing and consequent release of the locking means whereby said detonator registers with the priming hole 3 as a preliminary step to ignition.

When the parts are in their locked position, the piston rod 5 engages as illustrated in Fig. 1 the bore 13b in the detonator carrier 13 registering therewith so that said carrier is held in its locked position against the operation of the torsion spring 14a secured to the central spindle 14 of the carrier. In this position, the cap 15 of the detonator held by the carrier 13 lies outside the axial line passing through the priming hole 3a and the bore 13b engaged by the piston rod 5; the priming hole 3a is furthermore closed by a small cover 16 carried by the lower surface of the carrier 13 and secured to the latter. The small cover 16 is provided with a port 16a registering with the detonator. Above the detonator cap 15 a striker 17 is guided longitudinally inside a bore provided to this end inside the carrier 13, said striker being normally held in its inoperative position by a transverse rod adapted to be sheared.

The operation of the above described srtiker is as follows:

At the moment of the firing of a missile incorporating such a fuse, the inner piston 7 moves under the action of the axial acceleration of the missile towards the lower end of the fuse as a consequence of its inertia while it overcomes the resistance of the compression spring 8.

This produces a reduction in the pressure inside the chamber 7 bounded by the cooperating bottom sections of the two pistons 7 and'4-4a, said reduction in pressure cooperating with the resistance opposed by the spring 8 for breaking the movement of the piston 7. The sealing disc 9 freely carried by the piston rod 5 moves under the action of the axial acceleration more speedily than the piston 7 and is shifted therefore away from the latter. Thus air may enter the chamber 7a through the clearance between the bottom of the piston 7 and the piston rod 5, which clearance is no longer covered by the disc 9. Consequently, the piston 7 which is subjected to an axial acceleration with reference to the cylinders 1 to 3 of the fuse moves still further back and finally its bottom uncovers the locking ball 6 so that said ball 6 is allowed to drop inside the chamber 7a between the two piston bottoms. The piston 4-461 which was held up to this moment in its locked position illustrated in Fig. 1, is thus released and may slide axially with reference to the cylinder 1. At the moment at which the missile passes out of the mine-thrower-tube, the relative axial acceleration is cut off and consequently the compression spring 8 which has reached in the meantime its position of maximum compression has now a tendency to urge the sealing disc 9 outwardly and to return it into contact with the inner surface of the bottom of the piston 7 so that the central opening provided in the latter for the passage of the piston rod is now closed again in a fluidtight manner, through its inner end, by said disc 9. Under the action of the compression spring 8, the piston 7 moves now outwardly so that the air contained inside the chamber 7a is compressed, following which the piston 4a begins immediately moving in the same direction and compresses the air inside the outer chamber 11, at the outer end of the fuse.

By reason of the pressure permanently exerted by the spring 8, the two pistons are urged towards the diaphragm 10 while the air compressed inside the chambers 70 and 11 leaks out between the piston walls and the bores inside which the latter move.

The piston rod 5 moves with the piston 4-4a and, at the moment at which the latter has finished its stroke, said rod 5 no longer engages the bore 13b in the detonator carrier 13. Said carrier revolves then round its spindle 14 under the action of the torsion spring 14a. Following said rotation of the carrier 13 the striker 17 is substituted for the bore 13b in the location registering with the lower end of the piston rod 5 and the fuse is now ready to operate. At the moment of the impact of the missile, the diaphragm 10 is subjected to a pressure which urges the two pistons inwardly and consequently the piston rod 5 impinges on the striker 17 which shears the transverse rod 18 and ignites the detonator 15. The charge of the missile which is not illustrated is thus caused to explode since the flame passing through the priming hole 3a reaches the charge.

What I claim is:

1. A percussion fuse for ammunition, chiefly for mine thrower missiles, comprising a body provided with two coaxial cylindrical chambers communicating through a coaxial bore, a carrier adapted to revolve in the rear chamber around an axis parallel with and at distance from the axis of the chamber and provided with an axial bore adapted to register with the bore in the fuse body for a predetermined angular position of the carrier, a striker and a detonator longitudinally aligned therewith and carried by said carrier in register with the bore in the fuse body for another angular position of the carrier, means urging the carrier into its second last-mentioned position, two coaxial pistons fitted slidingly one inside the other, the outer piston being slidingly fitted in the front chamber of the fuse body, means locking the outer piston in its rearmost position with reference to the fuse body, a piston rod rigid with the outer piston passing through the inner piston with a clearance therebetween and extending for the rearmost position of the outer piston through the bore in the fuse body and through the bore in the carrier to hold the latter in the first :mentionzid angular position, the outer piston including a central projection on its inner side engaging the outer surface of the inner piston to form a small chamber between the two pistons, the air pressure in said chamber being subjected to a reduction at the starting of the missile under the action of the acceleration of the latter urging the inner piston rearwardly, a Washer slidingly fitted over the piston rod, a compression spring urging said washer into engagement with the inner surface of the inner piston to normally close the clearance between the latter and the piston rod, the rearward movement of the washer upon acceleration of the missile being higher than that of the inner piston which is braked by the said reduction pressure and uncovering said clearance, means whereby the outer piston, when released, is projected forwardly after a short delay through inertia to release the carrier with reference to the piston rod, and resilient means for registering said striker and detonator with the bore in the fuse body and with the piston rod and thereby to make said piston rod hit the striker-upon impact of the missile on the target.

V 21 A percussion fuse for ammunition, chiefly for mine thrower missiles, comprising a body provided with two coaxial cylindrical chambers communicating through a coaxial bore, a carrier adapted to revolve in the rear chamber round an axis parallel with and at distance from the axis of the. chambers and normally occupying a predetermined angular position, a striker and a detonator longitudinally aligned therewith and carried by said carrier to register with the bore in the fuse body for another angular position of the carrier, two coaxial pistons fitted slidingly one inside the other, the outer piston being slidingly fitted in the front chamber in the fuse body and including atpiston rod passing through the inner piston into register with the bore in the fuse body, locking means holding normally the outer piston in a predetermined position with reference to the fuse body, means wherethrough said outer piston, when in said predetermined position, locks the carrier in its first mentioned angular'setting, means controlled by the inner piston for releasing the locking means for the outer piston at the moment 'of thefiring of the missile under the action of the acceleration imparted thereto, and means whereby the outer piston, when released, is projected forwardly after a, short delay through inertia to release the carrier, a spring urging the carrier, when released, into its second position to make the striker and detonator register with the bore in the fuse body and with the piston rod, a diaphragm extending over the front of the chambers in the fuse body to the front of the pistons therein and forming with the latter a chamber in which last mentioned forward movement of the outer piston compresses air, the impact of the missile on a target urging said diaphragm back and acting through the air in last-mentioned chamber on the outer piston to make the piston rod recede into engagement with the striker registering therewith and thereby with the detonator.

3. A percussion fuse for a missile comprising a body having two coaxial cylindrical chambers communicating through a coaxial bore, a carrier in said rear chamber disposed to revolve around an axis parallel with and at distance from the axis of said chambers and normally occupying an initial angular position in said rear chamber, a striker, a detonator longitudinally aligned with said striker, said striker and said detonator being carried by said carrier for registration with the bore in the fuse body for a second angular position of the carrier, a torsion spring engaging said carrier urging the carrier into its second position, two coaxial pistons fitted slidingly one inside the other, the outer piston being slidingly fitted in the front chamber, said outer piston having a recess therein extending therethrough, a locking ball held inside said recess for engagement with a corresponding section of a wall of said front chamber to lock said outer piston in its rearmost position with reference to said fuse body, said outer piston including a central projection on its inner side engaging the outer surfacetof said inner piston to form a small chamber between said two pistons, the air pressure in said chamber being subjected to a reduction under acceleration urging said-inner piston rearwardly, a piston rod rigid with said outer piston and passing through said inner piston with a clearance therebetween and extending for the rearmost position of said outer piston through the chambers in said fuse body into engagement with said carrier to hold the latter in the initial position, the outer wall of said inner piston extending normally over and beyond said recess and being adapted to recede as a consequence of acceleration to the rear of the ball to allow the latter to drop into space between said two pistons and to release said outer piston, a washer slidingly fitted over the piston rod, a compression spring urging said washer into engagement with the inner surface of said inner piston to normally close the clearance between the latter and said piston rod, the rearward movement of the washer upon acceleration of the missile being higher than that of the inner piston which is braked by the said reduction in pressure and uncovering said clear- References Cited in the file of this patent UNITED STATES PATENTS 2,625,881 Rabinow Jan. 20, 1953 2,807,210 Wales Sept. 24, 1957 2,808,000 Lindsay Oct, 1, 1957 

